Coke plant tunnel repair and anchor distribution

ABSTRACT

A coke plant includes multiple coke ovens where each coke oven is adapted to produce exhaust gases, a common tunnel fluidly connected to the plurality of coke ovens and configured to receive the exhaust gases from each of the coke ovens, multiple standard heat recovery steam generators fluidly connected to the common tunnel where the ratio of coke ovens to standard heat recovery steam generators is at least 20:1, and a redundant heat recovery steam generator fluidly connected to the common tunnel where any one of the plurality of standard heat recovery steam generators and the redundant heat recovery steam generator is adapted to receive the exhaust gases from the plurality of ovens and extract heat from the exhaust gases and where the standard heat recovery steam generators and the redundant heat recovery steam generator are all connected in parallel with each other.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional App. No.62/786,194, filed Dec. 28, 2018, to U.S. Provisional App. No.62/786,157, filed Dec. 28, 2018, to U.S. Provisional App. No.62/786,096, filed Dec. 28, 2018, and to U.S. Provisional App. No.62/785,728, filed Dec. 28, 2018, the disclosures of which areincorporated herein by reference in their entirety and made part of thepresent disclosure.

TECHNICAL FIELD

The present disclosure relates to coke-making facilities and methods.

BACKGROUND

Coke is an important raw material used to make steel. Coke is producedby driving off the volatile fraction of coal, which is typically about25% of the mass. Hot exhaust gases generated by the coke making processare ideally recaptured and used to generate electricity. One style ofcoke oven which is suited to recover these hot exhaust gases areHorizontal Heat Recovery (HHR) ovens which have a unique environmentaladvantage over chemical byproduct ovens based upon the relativeoperating atmospheric pressure conditions inside the oven. HHR ovensoperate under negative pressure whereas chemical byproduct ovens operateat a slightly positive atmospheric pressure. Both oven types aretypically constructed of refractory bricks and other materials in whichcreating a substantially airtight environment can be a challenge becausesmall cracks can form in these structures during day-to-day operation.Chemical byproduct ovens are kept at a positive pressure to avoidoxidizing recoverable products and overheating the ovens. Conversely,HHR ovens are kept at a negative pressure, drawing in air from outsidethe oven to oxidize the coal volatiles and to release the heat ofcombustion within the oven. These opposite operating pressure conditionsand combustion systems are important design differences between HHRovens and chemical byproduct ovens. It is important to minimize the lossof volatile gases to the environment so the combination of positiveatmospheric conditions and small openings or cracks in chemicalbyproduct ovens allow raw coke oven gas (“COG”) and hazardous pollutantsto leak into the atmosphere. Conversely, the negative atmosphericconditions and small openings or cracks in the HHR ovens or locationselsewhere in the coke plant simply allow additional air to be drawn intothe oven or other locations in the coke plant so that the negativeatmospheric conditions resist the loss of COG to the atmosphere.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic drawing of a horizontal heat recovery (HHR) cokeplant, shown according to an exemplary embodiment.

FIG. 2 is a perspective view of portion of the HHR coke plant of FIG. 1,with several sections cut away.

FIG. 3 is a schematic drawing of a HHR coke plant, shown according to anexemplary embodiment.

FIG. 4 is a schematic drawing of a HHR coke plant, shown according to anexemplary embodiment.

FIG. 5 is a schematic drawing of a HHR coke plant, shown according to anexemplary embodiment.

FIG. 6 is a schematic drawing of a HHR coke plant, shown according to anexemplary embodiment.

FIG. 7 is a schematic view of a portion of the coke plant of FIG. 1.

FIG. 8 is an top plan view of a schematic of a coke plant.

FIG. 9 is top and side plan view of a portion of a common tunnel of theplant of FIG. 8.

FIG. 9A is a cross-sectional view of a common tunnel having a circularcross-sectional shape, as viewed along the cut-plane 9A-9A of FIG. 9.

FIG. 9B is a cross-sectional view of a common tunnel having an oblongcross-sectional shape, as viewed along the cut-plane 9A-9A of FIG. 9.

FIG. 9C is a cross-sectional view of a common tunnel having a bread-loafshaped cross-sectional shape, as viewed along the cut-plane 9A-9A ofFIG. 9.

FIG. 10 is a top and side plan view of another portion of a commontunnel of the plant of FIG. 8.

FIG. 11 is a perspective view of a conduit repair apparatus.

FIG. 12 is a perspective view of a replacement wall portion.

FIG. 13 is a cross-sectional schematic view of a replacement wallportion having a first type of anchor.

FIG. 14 is a cross-sectional schematic view of a replacement wallportion having a second type of anchor.

FIG. 15 is a perspective view of an interior surface of a tunnel sectionprior to gunning or shotcrete of refractory material.

FIG. 16 is a diagram illustrating an example heat distribution in atunnel wall.

FIG. 17 is a cross-section of an anchor having a ceramic portion.

FIG. 18 is a top plan view of an unrolled section of tunnel illustratingan exemplary anchor distribution pattern.

FIG. 19 is a schematic view of an interior of a tunnel wall illustratingan example anchor distribution pattern.

FIG. 20 is a flowchart illustrating an embodiment of a method ofrepairing a damaged portion of a tunnel or duct.

DETAILED DESCRIPTION

Referring to FIG. 1, a HHR coke plant 100 is illustrated which producescoke from coal in a reducing environment. In general, the HHR coke plant100 comprises at least one oven 105, along with heat recovery steamgenerators (HRSGs) 120 and an air quality control system 130 (e.g. anexhaust or flue gas desulfurization (FGD) system) both of which arepositioned fluidly downstream from the ovens and both of which arefluidly connected to the ovens by suitable ducts. The HHR coke plant 100preferably includes a plurality of ovens 105 and a common tunnel 110fluidly connecting each of the ovens 105 to a plurality of HRSGs 120.One or more crossover ducts 115 fluidly connects the common tunnel 110to the HRSGs 120. A cooled gas duct 125 transports the cooled gas fromthe HRSG to the flue gas desulfurization (FGD) system 130. Fluidlyconnected and further downstream are a baghouse 135 for collectingparticulates, at least one draft fan 140 for controlling air pressurewithin the system, and a main gas stack 145 for exhausting cooled,treated exhaust to the environment. Steam lines 150 interconnect theHRSG and a cogeneration plant 155 so that the recovered heat can beutilized. As illustrated in FIG. 1, each “oven” shown represents tenactual ovens.

More structural detail of each oven 105 is shown in FIG. 2 whereinvarious portions of four coke ovens 105 are illustrated with sectionscut away for clarity. Each oven 105 comprises an open cavity preferablydefined by a floor 160, a front door 165 forming substantially theentirety of one side of the oven, a rear door 170 preferably oppositethe front door 165 forming substantially the entirety of the side of theoven opposite the front door, two sidewalls 175 extending upwardly fromthe floor 160 intermediate the front 165 and rear 170 doors, and a crown180 which forms the top surface of the open cavity of an oven chamber185. Controlling air flow and pressure inside the oven chamber 185 canbe critical to the efficient operation of the coking cycle and thereforethe front door 165 includes one or more primary air inlets 190 thatallow primary combustion air into the oven chamber 185. Each primary airinlet 190 includes a primary air damper 195 which can be positioned atany of a number of positions between fully open and fully closed to varythe amount of primary air flow into the oven chamber 185. Alternatively,the one or more primary air inlets 190 are formed through the crown 180.In operation, volatile gases emitted from the coal positioned inside theoven chamber 185 collect in the crown and are drawn downstream in theoverall system into downcomer channels 200 formed in one or bothsidewalls 175. The downcomer channels fluidly connect the oven chamber185 with a sole flue 205 positioned beneath the over floor 160. The soleflue 205 forms a circuitous path beneath the oven floor 160. Volatilegases emitted from the coal can be combusted in the sole flue 205thereby generating heat to support the reduction of coal into coke. Thedowncomer channels 200 are fluidly connected to uptake channels 210formed in one or both sidewalls 175. A secondary air inlet 215 isprovided between the sole flue 205 and atmosphere and the secondary airinlet 215 includes a secondary air damper 220 that can be positioned atany of a number of positions between fully open and fully closed to varythe amount of secondary air flow into the sole flue 205. The uptakechannels 210 are fluidly connected to the common tunnel 110 by one ormore uptake ducts 225. A tertiary air inlet 227 is provided between theuptake duct 225 and atmosphere. The tertiary air inlet 227 includes atertiary air damper 229 which can be positioned at any of a number ofpositions between fully open and fully closed to vary the amount oftertiary air flow into the uptake duct 225.

In order to provide the ability to control gas flow through the uptakeducts 225 and within ovens 105, each uptake duct 225 also includes anuptake damper 230. The uptake damper 230 can be positioned at number ofpositions between fully open and fully closed to vary the amount of ovendraft in the oven 105. As used herein, “draft” indicates a negativepressure relative to atmosphere. For example, a draft of 0.1 inches ofwater indicates a pressure 0.1 inches of water below atmosphericpressure. Inches of water is a non-SI unit for pressure and isconventionally used to describe the draft at various locations in a cokeplant. If a draft is increased or otherwise made larger, the pressuremoves further below atmospheric pressure. If a draft is decreased,drops, or is otherwise made smaller or lower, the pressure moves towardsatmospheric pressure. By controlling the oven draft with the uptakedamper 230, the air flow into the oven from the air inlets 190, 215, 227as well as air leaks into the oven 105 can be controlled. Typically, anoven 105 includes two uptake ducts 225 and two uptake dampers 230, butthe use of two uptake ducts and two uptake dampers is not a necessity, asystem can be designed to use just one or more than two uptake ducts andtwo uptake dampers.

In operation, coke is produced in the ovens 105 by first loading coalinto the oven chamber 185, heating the coal in an oxygen depletedenvironment, driving off the volatile fraction of coal and thenoxidizing the volatiles within the oven 105 to capture and utilize theheat given off. The coal volatiles are oxidized within the ovens over a48-hour coking cycle, and release heat to regeneratively drive thecarbonization of the coal to coke. The coking cycle begins when thefront door 165 is opened and coal is charged onto the oven floor 160.The coal on the oven floor 160 is known as the coal bed. Heat from theoven (due to the previous coking cycle) starts the carbonization cycle.Preferably, no additional fuel other than that produced by the cokingprocess is used. Roughly half of the total heat transfer to the coal bedis radiated down onto the top surface of the coal bed from the luminousflame and radiant oven crown 180. The remaining half of the heat istransferred to the coal bed by conduction from the oven floor 160 whichis convectively heated from the volatilization of gases in the sole flue205. In this way, a carbonization process “wave” of plastic flow of thecoal particles and formation of high strength cohesive coke proceedsfrom both the top and bottom boundaries of the coal bed at the samerate, preferably meeting at the center of the coal bed after about 45-48hours.

Accurately controlling the system pressure, oven pressure, flow of airinto the ovens, flow of air into the system, and flow of gases withinthe system is important for a wide range of reasons including to ensurethat the coal is fully coked, effectively extract all heat of combustionfrom the volatile gases, effectively controlling the level of oxygenwithin the oven chamber 185 and elsewhere in the coke plant 100,controlling the particulates and other potential pollutants, andconverting the latent heat in the exhaust gases to steam which can beharnessed for generation of steam and/or electricity. Preferably, eachoven 105 is operated at negative pressure so air is drawn into the ovenduring the reduction process due to the pressure differential betweenthe oven 105 and atmosphere. Primary air for combustion is added to theoven chamber 185 to partially oxidize the coal volatiles, but the amountof this primary air is preferably controlled so that only a portion ofthe volatiles released from the coal are combusted in the oven chamber185 thereby releasing only a fraction of their enthalpy of combustionwithin the oven chamber 185. The primary air is introduced into the ovenchamber 185 above the coal bed through the primary air inlets 190 withthe amount of primary air controlled by the primary air dampers 195. Theprimary air dampers 195 can be used to maintain the desired operatingtemperature inside the oven chamber 185. The partially combusted gasespass from the oven chamber 185 through the downcomer channels 200 intothe sole flue 205 where secondary air is added to the partiallycombusted gases. The secondary air is introduced through the secondaryair inlet 215 with the amount of secondary air controlled by thesecondary air damper 220. As the secondary air is introduced, thepartially combusted gases are more fully combusted in the sole flue 205extracting the remaining enthalpy of combustion which is conveyedthrough the oven floor 160 to add heat to the oven chamber 185. Thenearly fully combusted exhaust gases exit the sole flue 205 through theuptake channels 210 and then flow into the uptake duct 225. Tertiary airis added to the exhaust gases via the tertiary air inlet 227 with theamount of tertiary air controlled by the tertiary air damper 229 so thatany remaining fraction of uncombusted gases in the exhaust gases areoxidized downstream of the tertiary air inlet 227.

At the end of the coking cycle, the coal has carbonized to produce coke.The coke is preferably removed from the oven 105 through the rear door170 utilizing a mechanical extraction system. Finally, the coke isquenched (e.g., wet or dry quenched) and sized before delivery to auser.

As shown in FIG. 1, a sample HHR coke plant 100 includes a number ofovens 105 that are grouped into oven blocks 235. The illustrated HHRcoke plant 100 includes five oven blocks 235 of twenty ovens each, for atotal of one hundred ovens. All of the ovens 105 are fluidly connectedby at least one uptake duct 225 to the common tunnel 110 which is inturn fluidly connected to each HRSG 120 by a crossover duct 115. Eachoven block 235 is associated with a particular crossover duct 115. Undernormal operating conditions, the exhaust gases from each oven 105 in anoven block 235 flow through the common tunnel 110 to the crossover duct115 associated with each respective oven block 235. Half of the ovens inan oven block 235 are located on one side of an intersection 245 of thecommon tunnel 110 and a crossover duct 115 and the other half of theovens in the oven block 235 are located on the other side of theintersection 245. Under normal operating conditions there will be littleor no net flow along the length of the common tunnel 110; instead, theexhaust gases from each oven block 235 will typically flow through thecrossover duct 115 associated with that oven block 235 to the relatedHRSG 120.

In the HRSG 120, the latent heat from the exhaust gases expelled fromthe ovens 105 is recaptured and preferably used to generate steam. Thesteam produced in the HRSGs 120 is routed via steam lines 150 to thecogeneration plant 155, where the steam is used to generate electricity.After the latent heat from the exhaust gases has been extracted andcollected, the cooled exhaust gases exit the HRSG 120 and enter thecooled gas duct 125. All of the HRSGs 120 are fluidly connected to thecooled gas duct 125. With this structure, all of the components betweenthe ovens 105 and the cooled gas duct 125 including the uptake ducts225, the common tunnel 110, the crossover duct 115 s, and the HRSGs 120form the hot exhaust system. The combined cooled exhaust gases from allof the HRSGs 120 flow to the FGD system 130, where sulfur oxides(SO_(x)) are removed from the cooled exhaust gases. The cooled,desulfurized exhaust gases flow from the FGD system 130 to the baghouse135, where particulates are removed, resulting in cleaned exhaust gases.The cleaned exhaust gases exit the baghouse 135 through the draft fan140 and are dispersed to the atmosphere via the main gas stack 145. Thedraft fan 140 creates the draft required to cause the described flow ofexhaust gases and depending upon the size and operation of the system,one or more draft fans 140 can be used. Preferably, the draft fan 140 isan induced draft fan. The draft fan 140 can be controlled to vary thedraft through the coke plant 100. Alternatively, no draft fan 140 isincluded and the necessary draft is produced due to the size of the maingas stack 145.

Under normal operating conditions, the entire system upstream of thedraft fan 140 is maintained at a draft. Therefore, during operation,there is a slight bias of airflow from the ovens 105 through the entiresystem to the draft fan 140. For emergency situations, a bypass exhauststack 240 is provided for each oven block 235. Each bypass exhaust stack240 is located at an intersection 245 between the common tunnel 110 anda crossover duct 115. Under emergency situations, hot exhaust gasesemanating from the oven block 235 associated with a crossover duct 115can be vented to atmosphere via the related bypass exhaust stack 240.The release of hot exhaust gas through the bypass exhaust stack 240 isundesirable for many reasons including environmental concerns and energyconsumption. Additionally, the output of the cogeneration plant 155 isreduced because the offline HRSG 120 is not producing steam.

In a conventional HHR coke plant when a HRSG is offline due to scheduledmaintenance, an unexpected emergency, or other reason, the exhaust gasesfrom the associated oven block can be vented to atmosphere through theassociated bypass exhaust stack because there is nowhere else for theexhaust gases to go due to gas flow limitations imposed by the commontunnel design and draft. If the exhaust gases were not vented toatmosphere through the bypass exhaust stack, they would cause undesiredoutcomes (e.g., positive pressure relative to atmosphere in an oven orovens, damage to the offline HRSG) at other locations in the coke plant.

In the HHR coke plant 100 described herein, it is possible to avoid theundesirable loss of untreated exhaust gases to the environment bydirecting the hot exhaust gases that would normally flow to an offlineHRSG to one or more of the online HRSGs 120. In other words, it ispossible to share the exhaust or flue gases of each oven block 235 alongthe common tunnel 110 and among multiple HRSGs 120 rather than aconventional coke plant where the vast majority of exhaust gases from anoven block flow to the single HRSG associated with that oven block.While some amount of exhaust gases may flow along the common tunnel of aconventional coke plant (e.g., from a first oven block to the HRSGassociated with the adjacent oven block), a conventional coke plantcannot be operated to transfer all of the exhaust gases from an ovenblock associated with an offline HRSG to one or more online HRSGs. Inother words, it is not possible in a conventional coke plant for all ofthe exhaust gases that would typically flow to a first offline HRSG tobe transferred or gas shared along the common tunnel to one or moredifferent online HRSGs. “Gas sharing” is possible by implementing anincreased effective flow area of the common tunnel 110, an increaseddraft in the common tunnel 110, the addition of at least one redundantHRSG 120R, as compared to a conventional HHR coke plant, and byconnecting all of the HRSGs 120 (standard and redundant) in parallelwith each other. With gas sharing, it is possible to eliminate theundesirable expulsion of hot gases through the bypass exhaust stacks240. In an example of a conventional HHR coke plant, an oven block oftwenty coke ovens and a single HRSG are fluidly connected via a firstcommon tunnel, two oven blocks totaling forty coke ovens and two HRSGsare connected by a second common tunnel, and two oven blocks totalingforty coke ovens and two HRSGs are connected by a third common tunnel,but gas sharing of all of the exhaust gases along the second commontunnel and along the third common tunnel from an oven block associatedwith an offline HRSG to the remaining online HRSG is not possible.

Maintaining drafts having certain minimum levels or targets with the hotexhaust gas sharing system is necessary for effective gas sharingwithout adversely impacting the performance of the ovens 105. The valuesrecited for various draft targets are measured under normal steady-stateoperating conditions and do not include momentary, intermittent, ortransient fluctuations in the draft at the specified location. Each oven105 must maintain a draft (“oven draft”), that is, a negative pressurerelative to atmosphere. Typically, the targeted oven draft is at least0.1 inches of water. In some embodiments, the oven draft is measured inthe oven chamber 185. During gas sharing along the common tunnel 110,the “intersection draft” at one or more of the intersections 245 betweenthe common tunnel 110 and the crossover ducts 115 and/or the “commontunnel draft” at one or more locations along the common tunnel 110 mustbe above a targeted draft (e.g., at least 0.7 inches of water) to ensureproper operation of the system. The common tunnel draft is measuredupstream of the intersection draft (i.e., between an intersection 245and the coke ovens 105) and is therefore typically lower than theintersection draft. In some embodiments the targeted intersection draftand/or the targeted common tunnel draft during gas sharing can be atleast 1.0 inches of water and in other embodiments the targetedintersection draft and/or the targeted common tunnel draft during gassharing can be at least 2.0 inches of water. Hot exhaust gas sharingeliminates the discharge of hot exhaust gases to atmosphere andincreases the efficiency of the cogeneration plant 155. It is importantto note that a hot exhaust gas sharing HHR coke plant 100 as describedherein can be newly constructed or an existing, conventional HHR cokeplant can be retrofitted according to the innovations described herein.

In an exhaust gas sharing system in which one or more HRSG 120 isoffline, the hot exhaust gases ordinarily sent to the offline HRSGs 120are not vented to atmosphere through the related bypass exhaust stack240, but are instead routed through the common tunnel 110 to one or moredifferent HRSGs 120. To accommodate the increased volume of gas flowthrough the common tunnel 110 during gas sharing, the effective flowarea of the common tunnel 110 is greater than that of the common tunnelin a conventional HHR coke plant. This increased effective flow area canbe achieved by increasing the inner diameter of the common tunnel 110 orby adding one or more additional common tunnels 110 to the hot exhaustsystem in parallel with the existing common tunnel 110 (as shown in FIG.3). In one embodiment, the single common tunnel 110 has an effectiveflow inner diameter of nine feet. In another embodiment, the singlecommon tunnel 110 has an effective flow inner diameter of eleven feet.Alternatively, a dual common tunnel configuration, a multiple commontunnel configuration, or a hybrid dual/multiple tunnel configuration canbe used. In a dual common tunnel configuration, the hot exhaust gassesfrom all of the ovens are directly distributed to two parallel, oralmost parallel, common tunnels, which can be fluidly connected to eachother at different points along the tunnels' length. In a multiplecommon tunnel configuration, the hot exhaust gasses from all of theovens are directly distributed to two or more parallel, or almostparallel common hot tunnels, which can be fluidly connected to eachother at different points along the tunnels' length. In a hybriddual/multiple common tunnel, the hot exhaust gasses from all of theovens are directly distributed to two or more parallel, or almostparallel, hot tunnels, which can be fluidly connected to each other atdifferent points along the tunnels' length. However, one, two, or moreof the hot tunnels may not be a true common tunnel. For example, one orboth of the hot tunnels may have partitions or be separated along thelength of its run.

Hot exhaust gas sharing also requires that during gas sharing the commontunnel 110 be maintained at a higher draft than the common tunnel of aconventional HHR coke plant. In a conventional HHR coke plant, theintersection draft and the common tunnel draft are below 0.7 inches ofwater under normal steady-state operating conditions. A conventional HHRcoke plant has never been operated such that the common tunnel operatesat a high intersection draft or a high common tunnel draft (at or above0.7 inches of water) because of concerns that the high intersectiondraft and the high common tunnel draft would result in excess air in theoven chambers. To allow for gas sharing along the common tunnel 110, theintersection draft at one or more intersections 245 must be maintainedat least at 0.7 inches of water. In some embodiments, the intersectiondraft at one or more intersections 245 is maintained at least at 1.0inches of water or at least at 2.0 inches of water. Alternatively oradditionally, to allow for gas sharing along the common tunnel 110, thecommon tunnel draft at one or more locations along the common tunnel 110must be maintained at least at 0.7 inches of water. In some embodiments,the common tunnel draft at one or more locations along the common tunnel110 is maintained at least at 1.0 inches of water or at least at 2.0inches of water. Maintaining such a high draft at one or moreintersections 245 or at one or more locations along the common tunnel110 ensures that the oven draft in all of the ovens 105 will be at least0.1 inches of water when a single HSRG 120 is offline and providessufficient draft for the exhaust gases from the oven block 235associated with the offline HRSG 120 to flow to an online HSRG 120.While in the gas sharing operating mode (i.e., when at least one HRSG120 is offline), the draft along the common tunnel 110 and at thedifferent intersections 245 will vary. For example, if the HRSG 120closest to one end of the common tunnel 110 is offline, the commontunnel draft at the proximal end of the common tunnel 110 will be around0.1 inches of water and the common tunnel draft at the opposite, distalend of the common tunnel 110 will be around 1.0 inches of water.Similarly, the intersection draft at the intersection 245 furthest fromthe offline HRSG 120 will be relatively high (i.e., at least 0.7 inchesof water) and the intersection draft at the intersection 245 associatedwith the offline HRSG 120 will be relatively low (i.e., lower than theintersection draft at the previously-mentioned intersection 245 andtypically below 0.7 inches of water).

Alternatively, the HHR coke plant 100 can be operated in two operatingmodes: a normal operating mode for when all of the HRSGs 120 are onlineand a gas sharing operating mode for when at least one of the HRSGs 120is offline. In the normal operating mode, the common tunnel 110 ismaintained at a common tunnel draft and intersection drafts similar tothose of a conventional HHR coke plant (typically, the intersectiondraft is between 0.5 and 0.6 inches of water and the common tunnel draftat a location near the intersection is between 0.4 and 0.5 inches ofwater). The common tunnel draft and the intersection draft can varyduring the normal operating mode and during the gas sharing mode. Inmost situations, when a HRSG 120 goes offline, the gas sharing modebegins and the intersection draft at one or more intersections 245and/or the common tunnel draft at one or more locations along the commontunnel 110 is raised. In some situations, for example, when the HRSG 120furthest from the redundant HRSG 120R is offline, the gas sharing modewill begin and will require an intersection draft and/or a common tunneldraft of at least 0.7 inches of water (in some embodiments, between 1.2and 1.3 inches of water) to allow for gas sharing along the commontunnel 110. In other situations, for example, when a HRSG 120 positionednext to the redundant HRSG 120R which is offline, the gas sharing modemay not be necessary, that is gas sharing may be possible in the normaloperating mode with the same operating conditions prior to the HRSG 120going offline, or the gas sharing mode will begin and will require onlya slight increase in the intersection draft and/or a common tunneldraft. In general, the need to go to a higher draft in the gas sharingmode will depend on where the redundant HRSG 120R is located relative tothe offline HRSG 120. The further away the redundant HRSG 120R fluidlyis form the tripped HRSG 120, the higher the likelihood that a higherdraft will be needed in the gas sharing mode.

Increasing the effective flow area and the intersection draft and/or thecommon tunnel draft to the levels described above also allows for moreovens 105 to be added to an oven block 235. In some embodiments, up toone hundred ovens form an oven block (i.e., are associated with acrossover duct).

The HRSGs 120 found in a conventional HHR coke plant at a ratio oftwenty ovens to one HRSG are referred to as the “standard HRSGs.” Theaddition of one or more redundant HRSGs 120R results in an overall ovento HRSG ratio of less than 20:1. Under normal operating conditions, thestandard HRSGs 120 and the redundant HRSG 120R are all in operation. Itis impractical to bring the redundant HRSG 120R online and offline asneeded because the start-up time for a HRSG would result in theredundant HRSG 120R only being available on a scheduled basis and notfor emergency purposes. An alternative to installing one or moreredundant HRSGs would be to increase the capacity of the standard HRSGsto accommodate the increased exhaust gas flow during gas sharing. Undernormal operating conditions with all of the high capacity HRSGs online,the exhaust gases from each oven block are conveyed to the associatedhigh capacity HRSGs. In the event that one of the high capacity HRSGsgoes offline, the other high capacity HRSGs would be able to accommodatethe increased flow of exhaust gases.

In a gas sharing system as described herein, when one of the HRSGs 120is offline the exhaust gases emanating from the various ovens 105 areshared and distributed among the remaining online HRSGs 120 such that aportion of the total exhaust gases are routed through the common tunnel110 to each of the online HRSGs 120 and no exhaust gas is vented toatmosphere. The exhaust gases are routed amongst the various HRSGs 120by adjusting a HRSG valve 250 associated with each HRSG 120 (shown inFIG. 1). The HRSG valve 250 can be positioned on the upstream or hotside of the HRSG 120, but is preferably positioned on the downstream orcold side of the HRSG 120. The HRSG valves 250 are variable to a numberof positions between fully opened and fully closed and the flow ofexhaust gases through the HRSGs 120 is controlled by adjusting therelative position of the HRSG valves 250. When gas is shared, some orall of the operating HRSGs 120 will receive additional loads. Because ofthe resulting different flow distributions when a HRSG 120 is offline,the common tunnel draft along the common tunnel 110 will change. Thecommon tunnel 110 helps to better distribute the flow among the HRSGs120 to minimize the pressure differences throughout the common tunnel110. The common tunnel 110 is sized to help minimize peak flowvelocities (e.g. below 120 ft/s) and to reduce potential erosion andacoustic concerns (e.g. noise levels below 85 dB at 3 ft). When an HRSG120 is offline, there can be higher than normal peak mass flow rates inthe common tunnel, depending on which HRSG 120 is offline. During suchgas sharing periods, the common tunnel draft may need to be increased tomaintain the targeted oven drafts, intersection drafts, and commontunnel draft.

In general, a larger common tunnel 110 can correlate to larger allowablemass flow rates relative to a conventional common tunnel for the samegiven desired pressure difference along the length of the common tunnel110. The converse is also true, the larger common tunnel 110 cancorrelate to smaller pressure differences relative to a conventionalcommon tunnel for the same given desired mass flow rate along the lengthof the common tunnel 110. Larger means larger effective flow area andnot necessarily larger geometric cross sectional area. Higher commontunnel drafts can accommodate larger mass flow rates through the commontunnel 110. In general, higher temperatures can correlate to lowerallowable mass flow rates for the same given desired pressure differencealong the length of the tunnel. Higher exhaust gas temperatures shouldresult in volumetric expansion of the gases. Since the total pressurelosses can be approximately proportional to density and proportional tothe square of the velocity, the total pressure losses can be higher forvolumetric expansion because of higher temperatures. For example, anincrease in temperature can result in a proportional decrease indensity. However, an increase in temperature can result in anaccompanying proportional increase in velocity which affects the totalpressure losses more severely than the decrease in density. Since theeffect of velocity on total pressure can be more of a squared effectwhile the density effect can be more of a linear one, there should belosses in total pressure associated with an increase in temperature forthe flow in the common tunnel 110. Multiple, parallel, fluidly connectedcommon tunnels (dual, multiple, or hybrid dual/multiple configurations)may be preferred for retrofitting existing conventional HHR coke plantsinto the gas sharing HHR coke plants described herein.

Although the sample gas-sharing HHR coke plant 100 illustrated in FIG. 1includes one hundred ovens and six HRSGs (five standard HRSGs and oneredundant HRSG), other configurations of gas-sharing HHR coke plants 100are possible. For example, a gas-sharing HHR coke plant similar to theone illustrated in FIG. 1 could include one hundred ovens, and sevenHRSGs (five standard HRSGs sized to handle the exhaust gases from up totwenty ovens and two redundant HRSGs sized to handle the exhaust gasesfrom up to ten ovens (i.e., smaller capacity than the single redundantHRSG used in the coke plant 100 illustrated in FIG. 1)).

As shown in FIG. 3, in HHR coke plant 255, an existing conventional HHRcoke plant has been retrofitted to a gas-sharing coke plant. Existingpartial common tunnels 110A, 110B, and 110C each connect a bank of fortyovens 105. An additional common tunnel 260 fluidly connected to all ofthe ovens 105 has been added to the existing partial common tunnels110A, 110B, and 110C. The additional common tunnel 260 is connected toeach of the crossover ducts 115 extending between the existing partialcommon tunnels 110A, 100B, and 110C and the standard HRSGs 120. Theredundant HRSG 120R is connected to the additional common tunnel 260 bya crossover duct 265 extending to the additional common tunnel 260. Toallow for gas sharing, the intersection draft at one or moreintersections 245 between the existing partial common tunnels 110A,110B, 110C and the crossover ducts 115 and/or the common tunnel draft atone or more location along each of the partial common tunnels 110A,110B, 110C must be maintained at least at 0.7 inches of water. The draftat one or more of the intersections 270 between the additional commontunnel 260 and the crossover ducts 115 and 265 will be higher than 0.7inches of water (e.g., 1.5 inches of water). In some embodiments, theinner effective flow diameter of the additional common tunnel 260 can beas small as eight feet or as large as eleven feet. In one embodiment,the inner effective flow diameter of the additional common tunnel 260 isnine feet. Alternatively, as a further retrofit, the partial commontunnels 110A, 110B, and 110C are fluidly connected to one another,effectively creating two common tunnels (i.e., the combination of commontunnels 110A, 110B, and 110C and the additional common tunnel 260).

As shown in FIG. 4, in HHR coke plant 275, a single crossover duct 115fluidly connects three high capacity HRSGs 120 to two partial commontunnels 110A and 110B. The single crossover duct 115 essentiallyfunctions as a header for the HRSGs 120. The first partial common tunnel110A services an oven block of sixty ovens 105 with thirty ovens 105 onone side of the intersection 245 between the partial common tunnel 110Aand the crossover duct 115 and thirty ovens 105 on the opposite side ofthe intersection 245. The ovens 105 serviced by the second partialcommon tunnel 110B are similarly arranged. The three high capacity HRSGsare sized so that only two HRSGs are needed to handle the exhaust gasesfrom all one hundred twenty ovens 105, enabling one HRSG to be takenoffline without having to vent exhaust gases through a bypass exhauststack 240. The HHR coke plant 275 can be viewed as having one hundredtwenty ovens and three HRSGs (two standard HRSGs and one redundant HRSG)for an oven to standard HRSG ratio of 60:1. Alternatively, as shown inFIG. 5, in the HHR coke plant 280, a redundant HRSG 120R is added to sixstandard HRSGs 120 instead of using the three high capacity HRSGs 120shown in FIG. 4. The HHR coke plant 280 can be viewed as having onehundred twenty ovens and seven HRSGs (six standard HRSGs and oneredundant HRSG) for an oven to standard HRSG ratio of 20:1). In someembodiments, coke plants 275 and 280 are operated at least duringperiods of maximum mass flow rates through the intersections 245 tomaintain a target intersection draft at one or more of the intersections245 and/or a target common tunnel draft at one or more locations alongeach of the common tunnels 110A and 110B of at least 0.7 inches ofwater. In one embodiment, the target intersection draft at one or moreof the intersections 245 and/or the target common tunnel draft at one ormore locations along each of the common tunnels 110A and 110B is 0.8inches of water. In another embodiment, the target intersection draft atone or more of the intersections 245 and/or the common tunnel draft atone or more locations along each of the common tunnels 110A and 110B is1.0 inches of water. In other embodiments, the target intersection draftat one or more of the intersections 245 and/or the target common tunneldraft at one or more locations along each of the common tunnels 110A and110B is greater than 1.0 inches of water and can be 2.0 inches of wateror higher.

As shown in FIG. 6, in HHR coke plant 285, a first crossover duct 290connects a first partial common tunnel 110A to three high capacity HRSGs120 arranged in parallel and a second crossover duct 295 connects asecond partial common tunnel 110B to the three high capacity HRSGs 120.The first partial common tunnel 110A services an oven block of sixtyovens 105 with thirty ovens 105 on one side of the intersection 245between the first partial common tunnel 110A and the first crossoverduct 290 and thirty ovens 105 on the opposite side of the intersection245. The second partial common tunnel 110B services an oven block ofsixty ovens 105 with thirty ovens 105 on one side of the intersection245 between the second common tunnel 110B and the second crossover duct295 and thirty ovens 105 on the opposite side of the intersection 245.The three high capacity HRSGs are sized so that only two HRSGs areneeded to handle the exhaust gases from all one hundred twenty ovens105, enabling one HRSG to be taken offline without having to ventexhaust gases through a bypass exhaust stack 240. The HHR coke plant 285can be viewed as having one hundred twenty ovens and three HRSGs (twostandard HRSGs and one redundant HRSG) for an oven to standard HRSGratio of 60:1 In some embodiments, coke plant 285 is operated at leastduring periods of maximum mass flow rates through the intersections 245to maintain a target intersection draft at one or more of theintersections 245 and/or a target common tunnel draft at one or morelocations along each of the common tunnels 110A and 110B of at least 0.7inches of water. In one embodiment, the target intersection draft at oneor more of the intersections 245 and/or the target common tunnel draftat one or more locations along each of the common tunnels 110A and 110Bis 0.8 inches of water. In another embodiment, the target intersectiondraft at one or more of the intersections 245 and/or the common tunneldraft at one or more locations along each of the common tunnels 110A and110B is 1.0 inches of water. In other embodiments, the targetintersection draft at one or more of the intersections 245 and/or thetarget common tunnel draft at one or more locations along each of thecommon tunnels 110A and 110B is greater than 1.0 inches of water and canbe 2.0 inches of water or higher.

FIG. 7 illustrates a portion of the coke plant 100 including anautomatic draft control system 300. The automatic draft control system300 includes an automatic uptake damper 305 that can be positioned atany one of a number of positions between fully open and fully closed tovary the amount of oven draft in the oven 105. The automatic uptakedamper 305 is controlled in response to operating conditions (e.g.,pressure or draft, temperature, oxygen concentration, gas flow rate)detected by at least one sensor. The automatic control system 300 caninclude one or more of the sensors discussed below or other sensorsconfigured to detect operating conditions relevant to the operation ofthe coke plant 100.

An oven draft sensor or oven pressure sensor 310 detects a pressure thatis indicative of the oven draft and the oven draft sensor 310 can belocated in the oven crown 180 or elsewhere in the oven chamber 185.Alternatively, the oven draft sensor 310 can be located at either of theautomatic uptake dampers 305, in the sole flue 205, at either oven door165 or 170, or in the common tunnel 110 near above the coke oven 105. Inone embodiment, the oven draft sensor 310 is located in the top of theoven crown 180. The oven draft sensor 310 can be located flush with therefractory brick lining of the oven crown 180 or could extend into theoven chamber 185 from the oven crown 180. A bypass exhaust stack draftsensor 315 detects a pressure that is indicative of the draft at thebypass exhaust stack 240 (e.g., at the base of the bypass exhaust stack240). In some embodiments, the bypass exhaust stack draft sensor 315 islocated at the intersection 245. Additional draft sensors can bepositioned at other locations in the coke plant 100. For example, adraft sensor in the common tunnel could be used to detect a commontunnel draft indicative of the oven draft in multiple ovens proximatethe draft sensor. An intersection draft sensor 317 detects a pressurethat is indicative of the draft at one of the intersections 245.

An oven temperature sensor 320 detects the oven temperature and can belocated in the oven crown 180 or elsewhere in the oven chamber 185. Asole flue temperature sensor 325 detects the sole flue temperature andis located in the sole flue 205. In some embodiments, the sole flue 205is divided into two labyrinths 205A and 205B with each labyrinth influid communication with one of the oven's two uptake ducts 225. A fluetemperature sensor 325 is located in each of the sole flue labyrinths sothat the sole flue temperature can be detected in each labyrinth. Anuptake duct temperature sensor 330 detects the uptake duct temperatureand is located in the uptake duct 225. A common tunnel temperaturesensor 335 detects the common tunnel temperature and is located in thecommon tunnel 110. A HRSG inlet temperature sensor 340 detects the HRSGinlet temperature and is located at or near the inlet of the HRSG 120.Additional temperature sensors can be positioned at other locations inthe coke plant 100.

An uptake duct oxygen sensor 345 is positioned to detect the oxygenconcentration of the exhaust gases in the uptake duct 225. An HRSG inletoxygen sensor 350 is positioned to detect the oxygen concentration ofthe exhaust gases at the inlet of the HRSG 120. A main stack oxygensensor 360 is positioned to detect the oxygen concentration of theexhaust gases in the main stack 145 and additional oxygen sensors can bepositioned at other locations in the coke plant 100 to provideinformation on the relative oxygen concentration at various locations inthe system.

A flow sensor detects the gas flow rate of the exhaust gases. Forexample, a flow sensor can be located downstream of each of the HRSGs120 to detect the flow rate of the exhaust gases exiting each HRSG 120.This information can be used to balance the flow of exhaust gasesthrough each HRSG 120 by adjusting the HRSG dampers 250 and therebyoptimize gas sharing among the HRSGs 120. Additional flow sensors can bepositioned at other locations in the coke plant 100 to provideinformation on the gas flow rate at various locations in the system.

Additionally, one or more draft or pressure sensors, temperaturesensors, oxygen sensors, flow sensors, and/or other sensors may be usedat the air quality control system 130 or other locations downstream ofthe HRSGs 120.

It can be important to keep the sensors clean. One method of keeping asensor clean is to periodically remove the sensor and manually clean it.Alternatively, the sensor can be periodically subjected to a burst,blast, or flow of a high pressure gas to remove build up at the sensor.As a further alternatively, a small continuous gas flow can be providedto continually clean the sensor.

The automatic uptake damper 305 includes the uptake damper 230 and anactuator 365 configured to open and close the uptake damper 230. Forexample, the actuator 365 can be a linear actuator or a rotationalactuator. The actuator 365 allows the uptake damper 230 to be infinitelycontrolled between the fully open and the fully closed positions. Theactuator 365 moves the uptake damper 230 amongst these positions inresponse to the operating condition or operating conditions detected bythe sensor or sensors included in the automatic draft control system300. This provides much greater control than a conventional uptakedamper. A conventional uptake damper has a limited number of fixedpositions between fully open and fully closed and must be manuallyadjusted amongst these positions by an operator.

The uptake dampers 230 are periodically adjusted to maintain theappropriate oven draft (e.g., at least 0.1 inches of water) whichchanges in response to many different factors within the ovens or thehot exhaust system. When the common tunnel 110 has a relatively lowcommon tunnel draft (i.e., closer to atmospheric pressure than arelatively high draft), the uptake damper 230 can be opened to increasethe oven draft to ensure the oven draft remains at or above 0.1 inchesof water. When the common tunnel 110 has a relatively high common tunneldraft, the uptake damper 230 can be closed to decrease the oven draft,thereby reducing the amount of air drawn into the oven chamber 185.

With conventional uptake dampers, the uptake dampers are manuallyadjusted and therefore optimizing the oven draft is part art and partscience, a product of operator experience and awareness. The automaticdraft control system 300 described herein automates control of theuptake dampers 230 and allows for continuous optimization of theposition of the uptake dampers 230 thereby replacing at least some ofthe necessary operator experience and awareness. The automatic draftcontrol system 300 can be used to maintain an oven draft at a targetedoven draft (e.g., at least 0.1 inches of water), control the amount ofexcess air in the oven 105, or achieve other desirable effects byautomatically adjusting the position of the uptake damper 230. Theautomatic draft control system 300 makes it easier to achieve the gassharing described above by allowing for a high intersection draft at oneor more of the intersections 245 and/or a high common tunnel draft atone or more locations along the common tunnel 110 while maintaining ovendrafts low enough to prevent excess air leaks into the ovens 105.Without automatic control, it would be difficult if not impossible tomanually adjust the uptake dampers 230 as frequently as would berequired to maintain the oven draft of at least 0.1 inches of waterwithout allowing the pressure in the oven to drift to positive.Typically, with manual control, the target oven draft is greater than0.1 inches of water, which leads to more air leakage into the coke oven105. For a conventional uptake damper, an operator monitors various oventemperatures and visually observes the coking process in the coke ovento determine when to and how much to adjust the uptake damper. Theoperator has no specific information about the draft (pressure) withinthe coke oven.

The actuator 365 positions the uptake damper 230 based on positioninstructions received from a controller 370. The position instructionscan be generated in response to the draft, temperature, oxygenconcentration, or gas flow rate detected by one or more of the sensorsdiscussed above, control algorithms that include one or more sensorinputs, or other control algorithms. The controller 370 can be adiscrete controller associated with a single automatic uptake damper 305or multiple automatic uptake dampers 305, a centralized controller(e.g., a distributed control system or a programmable logic controlsystem), or a combination of the two. In some embodiments, thecontroller 370 utilizes proportional-integral-derivative (“PID”)control.

The automatic draft control system 300 can, for example, control theautomatic uptake damper 305 of an oven 105 in response to the oven draftdetected by the oven draft sensor 310. The oven draft sensor 310 detectsthe oven draft and outputs a signal indicative of the oven draft to thecontroller 370. The controller 370 generates a position instruction inresponse to this sensor input and the actuator 365 moves the uptakedamper 230 to the position required by the position instruction. In thisway, the automatic control system 300 can be used to maintain a targetedoven draft (e.g., at least 0.1 inches of water). Similarly, theautomatic draft control system 300 can control the automatic uptakedampers 305, the HRSG dampers 250, and the draft fan 140, as needed, tomaintain targeted drafts at other locations within the coke plant 100(e.g., a targeted intersection draft or a targeted common tunnel draft).For example, for gas sharing as described above, the intersection draftat one or more intersections 245 and/or the common tunnel draft at oneor more locations along the common tunnel 110 needs to be maintained atleast at 0.7 inches of water. The automatic draft control system 300 canbe placed into a manual mode to allow for manual adjustment of theautomatic uptake dampers 305, the HRSG dampers, and/or the draft fan140, as needed. Preferably, the automatic draft control system 300includes a manual mode timer and upon expiration of the manual modetimer, the automatic draft control system 300 returns to automatic mode.

In some embodiments, the signal generated by the oven draft sensor 310that is indicative of the detected pressure or draft is time averaged toachieve a stable pressure control in the coke oven 105. The timeaveraging of the signal can be accomplished by the controller 370. Timeaveraging the pressure signal helps to filter out normal fluctuations inthe pressure signal and to filter out noise. Typically, the signal couldbe averaged over 30 seconds, 1 minute, 5 minutes, or over at least 10minutes. In one embodiment, a rolling time average of the pressuresignal is generated by taking 200 scans of the detected pressure at 50milliseconds per scan. The larger the difference in the time-averagedpressure signal and the target oven draft, the automatic draft controlsystem 300 enacts a larger change in the damper position to achieve thedesired target draft. In some embodiments, the position instructionsprovided by the controller 370 to the automatic uptake damper 305 arelinearly proportional to the difference in the time-averaged pressuresignal and the target oven draft. In other embodiments, the positioninstructions provided by the controller 370 to the automatic uptakedamper 305 are non-linearly proportional to the difference in thetime-averaged pressure signal and the target oven draft. The othersensors previously discussed can similarly have time-averaged signals.

The automatic draft control system 300 can be operated to maintain aconstant time-averaged oven draft within a specific tolerance of thetarget oven draft throughout the coking cycle. This tolerance can be,for example, +/−0.05 inches of water, +/−0.02 inches of water, or+/−0.01 inches of water.

The automatic draft control system 300 can also be operated to create avariable draft at the coke oven by adjusting the target oven draft overthe course of the coking cycle. The target oven draft can be stepwisereduced as a function of the elapsed time of the coking cycle. In thismanner, using a 48-hour coking cycle as an example, the target draftstarts out relatively high (e.g. 0.2 inches of water) and is reducedevery 12 hours by 0.05 inches of water so that the target oven draft is0.2 inches of water for hours 1-12 of the coking cycle, 0.15 inches ofwater for hours 12-24 of the coking cycle, 0.01 inches of water forhours 24-36 of the coking cycle, and 0.05 inches of water for hours36-48 of the coking cycle. Alternatively, the target draft can belinearly decreased throughout the coking cycle to a new, smaller valueproportional to the elapsed time of the coking cycle.

As an example, if the oven draft of an oven 105 drops below the targetedoven draft (e.g., 0.1 inches of water) and the uptake damper 230 isfully open, the automatic draft control system 300 would increase thedraft by opening at least one HRSG damper 250 to increase the ovendraft. Because this increase in draft downstream of the oven 105 affectsmore than one oven 105, some ovens 105 might need to have their uptakedampers 230 adjusted (e.g., moved towards the fully closed position) tomaintain the targeted oven draft (i.e., regulate the oven draft toprevent it from becoming too high). If the HRSG damper 250 was alreadyfully open, the automatic damper control system 300 would need to havethe draft fan 140 provide a larger draft. This increased draftdownstream of all the HRSGs 120 would affect all the HRSG 120 and mightrequire adjustment of the HRSG dampers 250 and the uptake dampers 230 tomaintain target drafts throughout the coke plant 100.

As another example, the common tunnel draft can be minimized byrequiring that at least one uptake damper 230 is fully open and that allthe ovens 105 are at least at the targeted oven draft (e.g. 0.1 inchesof water) with the HRSG dampers 250 and/or the draft fan 140 adjusted asneeded to maintain these operating requirements.

As another example, the coke plant 100 can be run at variable draft forthe intersection draft and/or the common tunnel draft to stabilize theair leakage rate, the mass flow, and the temperature and composition ofthe exhaust gases (e.g. oxygen levels), among other desirable benefits.This is accomplished by varying the intersection draft and/or the commontunnel draft from a relatively high draft (e.g. 0.8 inches of water)when the coke ovens 105 are pushed and reducing gradually to arelatively low draft (e.g. 0.4 inches of water), that is, running atrelatively high draft in the early part of the coking cycle and atrelatively low draft in the late part of the coking cycle. The draft canbe varied continuously or in a step-wise fashion.

As another example, if the common tunnel draft decreases too much, theHRSG damper 250 would open to raise the common tunnel draft to meet thetarget common tunnel draft at one or more locations along the commontunnel 110 (e.g., 0.7 inches water) to allow gas sharing. Afterincreasing the common tunnel draft by adjusting the HRSG damper 250, theuptake dampers 230 in the affected ovens 105 might be adjusted (e.g.,moved towards the fully closed position) to maintain the targeted ovendraft in the affected ovens 105 (i.e., regulate the oven draft toprevent it from becoming too high).

As another example, the automatic draft control system 300 can controlthe automatic uptake damper 305 of an oven 105 in response to the oventemperature detected by the oven temperature sensor 320 and/or the soleflue temperature detected by the sole flue temperature sensor or sensors325. Adjusting the automatic uptake damper 305 in response to the oventemperature and or the sole flue temperature can optimize cokeproduction or other desirable outcomes based on specified oventemperatures. When the sole flue 205 includes two labyrinths 205A and205B, the temperature balance between the two labyrinths 205A and 205Bcan be controlled by the automatic draft control system 300. Theautomatic uptake damper 305 for each of the oven's two uptake ducts 225is controlled in response to the sole flue temperature detected by thesole flue temperature sensor 325 located in labyrinth 205A or 205Bassociated with that uptake duct 225. The controller 370 compares thesole flue temperature detected in each of the labyrinths 205A and 205Band generates positional instructions for each of the two automaticuptake dampers 305 so that the sole flue temperature in each of thelabyrinths 205A and 205B remains within a specified temperature range.

In some embodiments, the two automatic uptake dampers 305 are movedtogether to the same positions or synchronized. The automatic uptakedamper 305 closest to the front door 165 is known as the “push-side”damper and the automatic uptake damper closet to the rear door 170 isknown as the “coke-side” damper. In this manner, a single oven draftpressure sensor 310 provides signals and is used to adjust both thepush- and coke-side automatic uptake dampers 305 identically. Forexample, if the position instruction from the controller to theautomatic uptake dampers 305 is at 60% open, both push- and coke-sideautomatic uptake dampers 305 are positioned at 60% open. If the positioninstruction from the controller to the automatic uptake dampers 305 is 8inches open, both push- and coke-side automatic uptake dampers 305 are 8inches open. Alternatively, the two automatic uptake dampers 305 aremoved to different positions to create a bias. For example, for a biasof 1 inch, if the position instruction for synchronized automatic uptakedampers 305 would be 8 inches open, for biased automatic uptake dampers305, one of the automatic uptake dampers 305 would be 9 inches open andthe other automatic uptake damper 305 would be 7 inches open. The totalopen area and pressure drop across the biased automatic uptake dampers305 remains constant when compared to the synchronized automatic uptakedampers 305. The automatic uptake dampers 305 can be operated insynchronized or biased manners as needed. The bias can be used to try tomaintain equal temperatures in the push-side and the coke-side of thecoke oven 105. For example, the sole flue temperatures measured in eachof the sole flue labyrinths 205A and 205B (one on the coke-side and theother on the push-side) can be measured and then corresponding automaticuptake damper 305 can be adjusted to achieve the target oven draft,while simultaneously using the difference in the coke- and push-sidesole flue temperatures to introduce a bias proportional to thedifference in sole flue temperatures between the coke-side sole flue andpush-side sole flue temperatures. In this way, the push- and coke-sidesole flue temperatures can be made to be equal within a certaintolerance. The tolerance (difference between coke- and push-side soleflue temperatures) can be 250° Fahrenheit, 100° Fahrenheit, 500Fahrenheit, or, preferably 250 Fahrenheit or smaller. Usingstate-of-the-art control methodologies and techniques, the coke-sidesole flue and the push-side sole flue temperatures can be brought withinthe tolerance value of each other over the course of one or more hours(e.g. 1-3 hours), while simultaneously controlling the oven draft to thetarget oven draft within a specified tolerance (e.g. +/−0.01 inches ofwater). Biasing the automatic uptake dampers 305 based on the sole fluetemperatures measured in each of the sole flue labyrinths 205A and 205B,allows heat to be transferred between the push side and coke side of thecoke oven 105. Typically, because the push side and the coke side of thecoke bed coke at different rates, there is a need to move heat from thepush side to the coke side. Also, biasing the automatic uptake dampers305 based on the sole flue temperatures measured in each of the soleflue labyrinths 205A and 205B, helps to maintain the oven floor at arelatively even temperature across the entire floor.

The oven temperature sensor 320, the sole flue temperature sensor 325,the uptake duct temperature sensor 330, the common tunnel temperaturesensor 335, and the HRSG inlet temperature sensor 340 can be used todetect overheat conditions at each of their respective locations. Thesedetected temperatures can generate position instructions to allow excessair into one or more ovens 105 by opening one or more automatic uptakedampers 305. Excess air (i.e., where the oxygen present is above thestoichiometric ratio for combustion) results in uncombusted oxygen anduncombusted nitrogen in the oven 105 and in the exhaust gases. Thisexcess air has a lower temperature than the other exhaust gases andprovides a cooling effect that eliminates overheat conditions elsewherein the coke plant 100.

As another example, the automatic draft control system 300 can controlthe automatic uptake damper 305 of an oven 105 in response to uptakeduct oxygen concentration detected by the uptake duct oxygen sensor 345.Adjusting the automatic uptake damper 305 in response to the uptake ductoxygen concentration can be done to ensure that the exhaust gasesexiting the oven 105 are fully combusted and/or that the exhaust gasesexiting the oven 105 do not contain too much excess air or oxygen.Similarly, the automatic uptake damper 305 can be adjusted in responseto the HRSG inlet oxygen concentration detected by the HRSG inlet oxygensensor 350 to keep the HRSG inlet oxygen concentration above a thresholdconcentration that protects the HRSG 120 from unwanted combustion of theexhaust gases occurring at the HRSG 120. The HRSG inlet oxygen sensor350 detects a minimum oxygen concentration to ensure that all of thecombustibles have combusted before entering the HRSG 120. Also, theautomatic uptake damper 305 can be adjusted in response to the mainstack oxygen concentration detected by the main stack oxygen sensor 360to reduce the effect of air leaks into the coke plant 100. Such airleaks can be detected based on the oxygen concentration in the mainstack 145.

The automatic draft control system 300 can also control the automaticuptake dampers 305 based on elapsed time within the coking cycle. Thisallows for automatic control without having to install an oven draftsensor 310 or other sensor in each oven 105. For example, the positioninstructions for the automatic uptake dampers 305 could be based onhistorical actuator position data or damper position data from previouscoking cycles for one or more coke ovens 105 such that the automaticuptake damper 305 is controlled based on the historical positioning datain relation to the elapsed time in the current coking cycle.

The automatic draft control system 300 can also control the automaticuptake dampers 305 in response to sensor inputs from one or more of thesensors discussed above. Inferential control allows each coke oven 105to be controlled based on anticipated changes in the oven's or cokeplant's operating conditions (e.g., draft/pressure, temperature, oxygenconcentration at various locations in the oven 105 or the coke plant100) rather than reacting to the actual detected operating condition orconditions. For example, using inferential control, a change in thedetected oven draft that shows that the oven draft is dropping towardsthe targeted oven draft (e.g., at least 0.1 inches of water) based onmultiple readings from the oven draft sensor 310 over a period of time,can be used to anticipate a predicted oven draft below the targeted ovendraft to anticipate the actual oven draft dropping below the targetedoven draft and generate a position instruction based on the predictedoven draft to change the position of the automatic uptake damper 305 inresponse to the anticipated oven draft, rather than waiting for theactual oven draft to drop below the targeted oven draft beforegenerating the position instruction. Inferential control can be used totake into account the interplay between the various operating conditionsat various locations in the coke plant 100. For example, inferentialcontrol taking into account a requirement to always keep the oven undernegative pressure, controlling to the required optimal oven temperature,sole flue temperature, and maximum common tunnel temperature whileminimizing the oven draft is used to position the automatic uptakedamper 305. Inferential control allows the controller 370 to makepredictions based on known coking cycle characteristics and theoperating condition inputs provided by the various sensors describedabove. Another example of inferential control allows the automaticuptake dampers 305 of each oven 105 to be adjusted to maximize a controlalgorithm that results in an optimal balance among coke yield, cokequality, and power generation. Alternatively, the uptake dampers 305could be adjusted to maximize one of coke yield, coke quality, and powergeneration.

Alternatively, similar automatic draft control systems could be used toautomate the primary air dampers 195, the secondary air dampers 220,and/or the tertiary air dampers 229 in order to control the rate andlocation of combustion at various locations within an oven 105. Forexample, air could be added via an automatic secondary air damper inresponse to one or more of draft, temperature, and oxygen concentrationdetected by an appropriate sensor positioned in the sole flue 205 orappropriate sensors positioned in each of the sole flue labyrinths 205Aand 205B.

As illustrated in FIG. 8, an HHR facility 400 can include multiple cokeovens 402. The coke ovens 402 can be arranged in one or more rows,clusters, or other arrangements. The coke ovens 402 can have many or allof the same features as the coke ovens 105 described above. The cokeovens 402 can be connected to one or more gas-sharing common tunnels 404via one or more ducts 405 (e.g., uptake ducts). The common tunnel(s) 404can have many or all of the same features as the above-described commontunnel 110. The ducts 405 can have many or all of the same features asthe above-described uptake ducts 225. The common tunnel 404 can beconnected to one or more HRSGs 409 along a length of the tunnel 404. TheHRSGs 409 can have many or all of the same features as theabove-described HRSGs 120. The facility 400 can include a cogenerationplant 411 connected to the common tunnel 404 and having many or all ofthe same features as the cogeneration plant 155 described above. Thefacility can include an exhaust facility 412 including an FGD system, abag house, a draft fan, and/or a main gas stack.

FIG. 9 illustrates portions of the common tunnel 404. As illustrated,the common tunnel 404 can include one or more joints 406. The joints 406can define the interfaces between consecutive tunnel portions 404.Utilizing joints 406 can allow for construction and manipulation ofsmaller finite tunnel portions to be joined on-site. In someembodiments, some or all portions of the common tunnel 404 areprefabricated off-site and shipped to the installation site prior tofinal assembly. In some embodiments, one or more of the joints 406 areflexible joints 406F. The flexible joints 406F can be configured to flexin response to stresses on the tunnel 404. Such stresses can includethermal stresses, seismic stresses, and/or other stresses realizedduring installation or use of the HHR facility 400. As used in thiscontext, “flex” of the tunnel 404 include movement of adjacent tunnelportions 404 with respect to each other in an axial, rotational, and/orbending manner. In some embodiments, one or more braces 410 can be usedto support the tunnel 404. The braces 410 can be positioned along thelength of the tunnel 404 under joints 406 and/or between joints 406.

In some embodiments, as illustrated in FIG. 9A, the common tunnel 404can have a circular cross-sectional shape. The common tunnel 404 canhave a radius R1 (e.g., the radius of the common tunnel 404 as measuredto the outer surface of the common tunnel 404) of greater than aboutthree feet, greater than about four feet, greater than about five feet,greater than about six feet, greater than about eight feet, greater thanabout ten feet, and/or greater than about twelve feet In someembodiments, the radius R1 of the common tunnel 404 is between about twoto five feet, between about three to eight feet, between about two tonine feet, and/or between about four to ten feet.

In some embodiments, as illustrated in FIG. 9B, the common tunnel 404has an oblong (e.g., egg-shape) or elliptical cross-sectional shape. Forexample, the common tunnel 404 may have an oblong cross-sectional shapewith a maximum radius R2 (e.g., measured to an outer surface of thecommon tunnel 404) and a minimum radius R3 (e.g., measured to an outersurface of the common tunnel 404) smaller than the maximum radius R2.The maximum radius R2 can be greater than about three feet, greater thanabout four feet, greater than about five feet, greater than about sixfeet, greater than about eight feet, greater than about ten feet, and/orgreater than about twelve feet. In some embodiments, the maximum radiusR2 of the common tunnel 404 is between about two to five feet, betweenabout three to eight feet, between about two to nine feet, and/orbetween about four to ten feet. The minimum radius R3 can be greaterthan about two feet, greater than about three feet, greater than aboutfive feet, greater than about six feet, greater than about eight feet,greater than about ten feet, and/or greater than about twelve feet. Insome embodiments, the minimum radius R3 of the common tunnel 404 isbetween about one to six feet, between about two to eight feet, betweenabout three to nine feet, and/or between about four to ten feet. Themaximum radius R2 of the cross-section of the common tunnel 404 can beat least 10% greater, at least 20% greater, at least 30% greater, atleast 50% greater, at least 75% greater, and/or at least 100% greaterthan the minimum radius R3 of the cross-section of the common tunnel404.

In some embodiments, as illustrated in FIG. 9C, the common tunnel 404has a cross-sectional shape having one or more flat sides, corners,and/or curved sides. For example, the common tunnel 404 can have a lowerrectangular portion 404 a and an upper curved portion 404 b (e.g., abread loaf shape). In some embodiments, lower portion 404 a of thecommon tunnel 404 has a width W1 greater than about six feet, greaterthan about eight feet, greater than about ten feet, greater than abouttwelve feet, greater than about sixteen feet, greater than abouteighteen feet, and/or greater than about twenty feet. In someembodiments, the width W1 of the common tunnel 404 (e.g., of the lowerportion 404 a) is between about three to ten feet, between about four tofifteen feet, between about six to eighteen feet, and/or between abouteight to twenty feet. The common tunnel 404 can have a height H1 greaterthan about six feet, greater than about eight feet, greater than aboutten feet, greater than about twelve feet, greater than about sixteenfeet, greater than about eighteen feet, and/or greater than about twentyfeet. In some embodiments, the height H1 of the common tunnel 404 isbetween about five to twelve feet, between about seven to fifteen feet,between about nine to sixteen feet, and/or between about six to twentyfeet. The curved portion 404 b can have a radius of curvature R4. Insome embodiments, the radius of curvature R4 is constant across thecurved upper surface. In some embodiment, the radius of curvature R4varies. For example, the radius of curvature R4 can have a maximum at ornear the apex of the curved portion of the tunnel and a minimum at ornear the junctions between the curved portion 404 b and the rectangularportion 404 a.

In some applications, portions of the tunnel 404 are bent or otherwisenot straight. For example, as illustrated in FIGS. 8 and 10, the commontunnel 404 includes one or more bends 412. Bends or other redirectionscan be used to guide the common tunnel 404 or other conduit around otherstructures of the HHR facility 400. In some embodiments, joints 406,406F are positioned adjacent the bends 412 to facilitate connection ofthe bent tunnel portions with straight tunnel portions.

Due to high temperatures, continuous operation, and/or other operationaland/or environmental factors, it may be desirable or necessary to repairor replace certain portions of the common tunnel 404. Replacement ofdamaged portions can allow for cost-effective repair of the commontunnel 404 without overhaul of large portions of the tunnel 404. In somecases, replacement of a length of tunnel may be desired or necessary. Inother cases, replacement of only a portion of a tunnel wall (e.g., lessthan an entire annulus) may be desired or necessary.

FIG. 11 illustrates an embodiment of a machine 422 used to constructand/or repair the common tunnel 404. As illustrated, the machine 422 canbe a crane or other construction equipment configured to movelarge/heavy components. The machine 422 can be used to remove damagedtunnel portions and/or to position replacement tunnel portions 420 at arepair site.

In some embodiments, as illustrated in FIG. 12, a replacement tunnelportion 426 includes an outer wall portion 428. The outer wall portion428 of the replacement tunnel portion 426 can be constructed from steelor some other material. In some embodiments, the outer wall portion 428is constructed from the same material as the outer wall of thesurrounding tunnel 404. Preferably, the radially-inward surface of theouter wall portion 428 is coated with a mastic material or othercorrosion-resistant material configured to reduce the risk of corrosionof the outer wall portion 428 (e.g., in the event of hot/corrosive gasgaining access to the outer wall portion 428). In some embodiments, theuse of a mastic coating on the inner surface of the outer wall portion428 (e.g., and on the inner surface of the originally-installed tunnel)can allow the outer wall portion 428 to be kept at a cooler temperaturethan would be advisable if mastic were not used. For example, acidiccondensation may occur within the tunnel when temperatures go below 350°F. The mastic material coating can resist corrosion caused by the acidiccondensation, thereby allowing the outer wall portion 428 to remain atlower temperatures (e.g., 200-250° F.). In some embodiments, the outerwall portion 428 is pre-rolled to match the curvature of the adjacenttunnel 404. In some embodiments, the outer wall portion 428 is rolledon-site as part of the installation and repair process.

In some embodiments, the replacement tunnel portion 426 includes abacker board 432 positioned radially inward from the outer wall portion428. In some applications, a layer of low thermal conductivity materialis used instead of or in addition to one or more layers of backer board432. For example, bricks, insulating fire bricks (IFBs), paper, fiber,and/or other insulating and/or flexible insulating materials may beused. The backer board 432 can be constructed from a refractory materialor other material (e.g., 60-M refractory material or Rescocast 8material). Preferably, the backer board 432 has a low thermalconductivity. In some embodiments, the replacement tunnel portion 424includes a plurality of backer boards 432 positioned adjacent eachother. The backer board(s) 432 can be scored (e.g., on aradially-outward surface) to increase flexibility of the backer board(s)432. Increasing flexibility of the backer board(s) can allow for betterfit between the backer board(s) 432 and the outer wall portion 428. Insome embodiments, a second layer of backer board is used. In someembodiments, the backer board(s) are either provided as or cut intostrips prior to installation. The second layer of backer board can bepositioned radially-inward from the illustrated backer board(s) 432. Aswith the backer board(s) 432, the second layer of backer board mayinclude multiple pieces of backer board, may be scored, may beconstructed from a refractory material or other material (e.g., 60-Mrefractory material or Rescocast 8 refractory material), and/or has alow thermal conductivity.

The replacement tunnel portion 426 can include anchors 430 extendingradially inward from the outer wall portion 428. In embodiments wherebacker board 432 is used, the anchors 430 can extend through the backerboard 432. As explained below with respect to FIGS. 13-14, the anchors430 can be used to retain gunned or shotcrete material (e.g., refractorymaterial) that is applied to an inner surface of the outer wall portion428 and/or to an inner surface of the backer board 432. In someembodiments, the anchors 430 are configured to retain the backer board432 in place with respect to the outer wall portion 428. In someembodiments, one or both of the backer board 432 and thegunned/shotcrete material are replaced with refractory bricks (e.g.,fiberglass bricks) or other materials.

FIGS. 13-14 illustrate embodiments of anchors 430, 430′ that can be usedwith a replacement tunnel portion 426. For example, the anchor 430illustrated in FIG. 13 is connected to an inner surface of the outerwall portion 428. The anchor 430 can include an anchor body 434 (e.g.,an elongate body). The anchor body 434 can be constructed from a metal(e.g., steel, 304 stainless steel, 310 stainless steel, 330 stainlesssteel, etc.) or other material (e.g., ceramic, refractory, etc.). Theanchor 430 can include one or more prongs 436 extending from an end ofthe anchor body 434 opposite the attachment to the outer wall portion428. The prongs 436 can include one or more bends, waves, turns, twists,and/or other geometric features. These geometric features can increasethe purchase of the prongs 436 with respect to the backer board(s)and/or other insulative/refractory materials in the tunnel portion 426.Attachment of the anchor 430 to the inner surface of the outer wallportion can be performed, for example, via welding. Preferably a fullfillet weld 438 (or some other annular or partially-annular weld) isused to connect the anchor 430 to the outer wall 428.

The anchor 430 can have an overall length L1, as measured along a radiusof the tunnel 404 and/or normal to the surface of the outer wall 428 towhich the anchor 430 is attached. The length L1 includes the length ofthe prong(s) 436. As illustrated, the length of the anchor 430 extendsbeyond an inner surface of the refractory board 432. In someembodiments, the length L1 of the anchor 430 is between 2-6 inches,between 3-8 inches, between 1-14 inches, between 2.5-9 inches, and/orbetween 4-10 inches. In some embodiments, some anchors have lengthslonger than other anchors. For example, it may be preferred to uselonger anchors at or near seams between sections of the tunnels andducts of a given system, as failures in the refractory and/or otherinsulative material occur more frequently at or near seams. Using longeranchors at or near seams in the tunnel/duct can reduce the risk ofrebound of gunned insulative material at or near the seams.

In some embodiments, anchor length can be used to manipulate/modify theshape of the internal walls of tunnels in the coke plant. For example,using longer anchors at and/or near internal corners can smooth out theinternal bends in a tunnel, thereby reducing the tortuousness of the airflow paths through the tunnel.

In some embodiments, an overall thickness T1 of the refractory material(e.g., the backer board 432 (or multiple layers of backer board) and/orthe gunned/shotcrete refractory material 440) is approximately 6 inches.In some embodiments, the overall thickness T1 of the refractory materialis between 1-8 inches, between 2-10 inches, between 5-9 inches, and/orbetween 4-15 inches.

The thickness T2 of the backer board 432, if used, can be approximately2 inches. In some embodiments, the thickness T2 of the backer board 432is between 1-5 inches, between 0.5-6 inches, between 3-5 inches, and/orbetween 2.5-7.5 inches.

The thickness T3 of the gunned/shotcrete refractory material 440 can beapproximately 4 inches. In some embodiments, the thickness T3 of therefractory material 440 is between 1-8 inches, between 2-5 inches,between 3-7 inches, and/or between 1.5-15 inches. In some applications,replacement tunnel portions 426 are installed without backer boards. Insuch applications, the thickness T3 of the gunned/shotcrete refractorymaterial 440 may be increased as compared to applications where backerboard(s) are utilized. In some applications, whether with or withoutbacker board(s), multiple layers of gunned/shotcrete materials may beused. For example, a first (e.g., outer) gunned/shotcrete layer maycomprise a first material and a second (e.g., inner) gunned/shotcretelayer may be deposited on an inner surface of the first material. Insome applications, wherein bricks, IFBs, or other materials are usedinstead of or in addition to the backer board(s) 432, it may bepreferable to have a thin layer of gunned/shotcrete refractory material440.

The overall thickness T1 of the insulating materials used in the tunnelmay be limited by the resulting inner diameter of the insulatingmaterials, which forms the inner diameter of the tunnel. For example,reducing the inner diameter of the tunnel (e.g., the common tunnel orother tunnel) can reduce the amount of draft through the tunnel andthereby reduce the flow rate of gases through the tunnel. Reducing thedraft through the tunnel can cause stagnation of gases (e.g., hot,corrosive, and/or otherwise harmful gases) within the tunnel, therebydamaging the insulating materials and/or other portions of the tunnel.Increasing the thickness of the insulating material can also decreasethe temperature of the outer shell of the tunnel, which can lead tocondensation of the corrosive gases on the outer shell. In someembodiments, increasing the thickness T1 of the insulating material canallow for use of cheaper/lower performance insulating materials (e.g.,materials with a lower insulative value), as the thickness of thosematerials can offset the inefficiencies of the materials. In someembodiments, reducing the thickness T1 of the insulating materials canincrease the temperature of the outer shell, thereby leading tobreakdown of the outer shell material. Accordingly, a balance betweenthickness and performance is desirable. Such desirable balances aredescribed above with respect to FIG. 13.

It is preferable that there be a distance D1 (e.g. a radial distance)between the innermost end of the anchors 430 and the inner surface ofthe refractory material 440. In other words, is it preferably to havesome thickness of refractory material 440 between the anchor 430 and theopen, hot tunnel. In some embodiments, the distance D1 between theanchors 430 and the open tunnel is at least 1 inches, at least 2 inches,at least 3 inches, at least 4 inches, at least 5 inches, and/or at least8 inches. Insulating the anchors 430 from the hot gases in the tunnel404 can reduce the likelihood that the anchors 430 are damaged by heat,chemical reaction, or otherwise. While the wall and anchor structure ofFIG. 13 is described above with respect to replacement wall portions, itwill be understood that this same wall and anchor structure can be usedfor original tunnel structure upon original installation and/orexpansion of an HHR coke plant facility.

FIG. 14 illustrates an anchor 430′ having many similar features to theanchor 430 described above. As such, like reference numeral with respectto FIG. 13 refer to components that can be similar to or identical tothose components described above with the same reference numerals. Onedifference between the anchor 430′ of FIG. 14 and the anchor 420 of FIG.13 is that the anchor 430′ of FIG. 14 is inserted through the outer wall428 of the replacement tunnel portion 426. In such configurations, holes442 or other apertures are formed/drilled in the outer wall portion 428,through which the anchors 430 are inserted. Preferably, the radiallyoutermost portion of the anchors 430 are sealed and/or secured to theouter wall portion 428 via welds 438′ or other attachment material,structures, and/or methods. The welds 438′ can be, for example, fullfillet welds or other appropriate welds. The overall length L1′ of theanchor 430′ can be similar to and/or greater than the overall length L1of the anchor 430 described above to accommodate the extension of theanchor 430 outside and through the outer wall portion 428. While thewall and anchor structure of FIG. 14 is described above with respect toreplacement wall portions, it will be understood that this same wall andanchor structure can be used for original tunnel structure upon originalinstallation and/or expansion of an HHR coke plant facility.

FIG. 15 illustrates an embodiment of a tunnel portion having a pluralityof anchors 450. The tunnel portion can be a replacement portion or anoriginal tunnel portion. The anchors 450 can many or all of the featuresof the anchors 430, 430′ described above. The anchors 450, asillustrated, can be distributed along the outer wall 452 in adistribution pattern. For example, the anchors 450 can be arranged instaggered rows. In some applications, the anchors 450 are distributed inevenly-spaced and/or non-staggered rows. As discussed in more detailbelow, the spacing between the anchors 450 can vary along the curvatureof the outer wall 452. For example, the spacing between the anchors 450can decrease the closer the anchors 450 are to the top of the outer wall452 and/or the closer the anchors 450 are to a joint with another tunnelsection.

FIG. 15 also illustrates an example of a multi-layered wall portion. Forexample, the tunnel wall can have a first insulation/refractory layer454 positioned radially inward from the outer wall. Second and/or thirdlayers 456, 458 of insulation/refractory material can be positionedradially inward from the first layer 454. One or more of the layers maybe a backer board and one or more of the layers may be gunned/shotcretematerial. One or more of the layers may comprise bricks, (IFBs), paper,fiber, and/or other insulating and/or flexible insulating materials.

As illustrated in FIG. 16, an installed anchor 450 can be subject toextreme heating during use. For example, the prongs 460 or otherradially-innermost portion of the anchor 450 (e.g., the top of theanchor 450 in the frame of reference of FIG. 16) can be subject totemperatures in excess of 2000° F.

In some applications, as illustrated in FIG. 17, it may be desirable touse one or more anchors 462 having ceramic or other insulativematerials. For example, the anchor 462 can include an anchor body 464attached to the outer wall 466 via welding 468 or other attachmentmechanisms/methods. The anchor body 464 can be constructed from a metal(e.g., steel, 304 steel, 310 steel, 316 steel, 330 steel, stainlesssteel, etc.) or other material (e.g., ceramic, refractory, etc.). Theanchor 462 can include a clip 470 or other attachment structure at ornear an end of the anchor body 464 opposite the outer wall 466. The clip470 can be constructed from a metal (e.g., steel, 322 stainless steel,etc.) or other material. The clip 470 can retain an insulative anchoringportion 472. The insulative anchoring portion 472 can be constructedfrom a ceramic, fiberglass, composite, brick, and/or other material orcombination of materials. In some embodiments, the insulative anchoringportion 472 includes one or more geometric features (e.g., protrusions,ridges, indentations, wings, projections, channels, grooves, etc.)configured to increase purchase of the insulative anchoring portion 472in the backer board(s) and/or refractory material of the tunnel wall. Insome embodiments, anchors 462 having insulative anchoring portions 472are used in tunnel locations subject to higher temperatures than othertunnel sections. In some embodiments, anchors 462 with insulativeanchoring portions 472 are distributed amongst other anchors 450 havingmetal prongs or other configurations. For example, one out of every two,three, four, five, six, seven, eight, nine, ten, or more anchors can beanchors 462 with insulative anchoring portions 472.

In many applications, it may be desirable to use a higher anchor density(e.g., smaller spacing between anchors or more anchors per area) at ornear the top of a tunnel portion. For example, the need for anchors canincrease as the alignment between the Earth's gravitational force getscloser to perpendicular to the inner surface of the outer wall of thetunnel. FIG. 18 illustrates a varied anchor density pattern for a tunnelportion 478. The tunnel portion 478 is illustrated in a flat orpre-rolled configuration wherein the longitudinal center 484 correspondsto the bottom of the tunnel portion 478 after rolling and installation.As illustrated, first and second ends 480 a, 480 b of the tunnel portion478, which correspond to the top of the tunnel portion 478 after rollingand installation, have a high anchor density, while the longitudinalcenter 484 is devoid of anchors. In some embodiments, one or anchors maybe found in the longitudinal center 484 of the tunnel portion 478. Asillustrated, an intermediate portion 483 of the tunnel portion 478between the top and bottom can include an intermediate anchor density.In some embodiments, the lower portion of the tunnel 478 is devoid ofanchors. This lower portion can be the lower 240°, the lower 200°, thelower 180°, the lower 160°, the lower 120% the lower 90°, the lower 30°,or more. The portions of the tunnel portion 478 near the windows 485 canhave increased anchor density to hold the insulative material in place.

FIG. 19 schematically illustrates an example of anchor densitydistribution on a tunnel portion 488. As illustrated, the anchor densityvaries between a maximum density Dmax along the top-most line 490 of thetunnel portion 488 and along a joint 492, and a minimum anchor densityDmin. The maximum anchor density Dmax can have an average spacingbetween anchors of less than 8 inches, less than 10 inches, less than 7inches, less than 6 inches, and/or less than 3 inches. The minimumanchor density Dmin can have an average spacing between anchors of atleast 3 inches, at least 5 inches, at least 6 inches, at least 10inches, and/or at least 15 inches. In some embodiments, Dmin is infiniteas a portion of the tunnel has no anchors. The median anchor densityDmed can be an anchor spacing between 6-12 inches, between 8-10 inches,between 7-11 inches, between 4-15 inches, and/or between 9-10 inches. Insome embodiments, two or more anchors touch each other during and/orafter installation.

The tunnel wall and anchor constructions and distributions described andillustrated in FIGS. 12-19 and the corresponding text can be used inreplacement wall portions and/or in new tunnel construction. In someembodiments, the tunnel wall and anchor constructions described hereincan be utilized in tunnel replacement/upgrade procedures.

In some embodiments, a method of repairing the common tunnel 404 or someother conduit can include identifying damaged portions of the tunnel404. For example, external damage may be visible to the naked eye. Insome cases, warping, bubbling, bowing, and/or other imperfections areformed on the wall of the tunnel 404. Thermal imaging may be used inconjunction with external observation to identify hot spots and otherareas of potential damage. In some cases, the anchors of the tunnel areviewable via infrared. Anchors with elevated temperature can indicatedamaged refractory material or other damage to the tunnel.

Upon identification of the damaged portion of the tunnel 404, anoperator may choose to remove a portion of the tunnel wall larger thanthe observed damaged area. Removal of the damaged portion may includecutting, drilling, sawing, chain-sawing, and/or other methods ofremoval. A crane of other instrument may be used to lift the damagedportion from the tunnel.

A replacement tunnel portion, similar to or the same as the replacementtunnel portions described above, may be sized and shaped to replace thedamaged portion. In some embodiments, the desired size and shape is anaxial length of annular tunnel. In some embodiments, the desired sizeand shape is a portion of a wall. Preferably, the outer wall portion ofthe replacement tunnel portion is sized to be slightly larger than theremoved outer wall portion of the damaged tunnel. Using a slightlylarger outer wall can allow for complete perimeter welding between thereplacement tunnel portion and the adjacent tunnel.

Upon placement of the replacement tunnel portion at the desiredlocation, the outer wall of the replacement tunnel portion can bespot-welded or fully welded to the adjoining tunnel portions. Refractorymaterial can be gunned or shotcrete onto the inner surface of the outerwall portion or refractory board. Gunning the refractory material caninclude mixing the material with water at the outlet of the dispenser.Shotcreting, on the other hand, includes mixing the water with therefractory material before the outlet of the dispenser. If the outerwall was only spot-welded prior to dispensing the refractor material,the outer wall of the replacement tunnel portion can then be welded tothe adjacent tunnel around an entire perimeter of the replacement tunnelportion.

In some embodiments, the gunning/shotcrete is performed through openings408 (FIG. 9) in the tunnel 404. In some embodiments, openings are formedas desired and needed.

FIG. 20 illustrates a method of repairing the common tunnel. Asdescribed above, an imaging device (e.g., an infrared camera, FLIR®camera, or other imaging device) can be used to identify damagedportions of the common tunnel (step S1). These damaged portions areoften viewable as areas of increased temperature on the outer surface ofthe tunnel and/or as physically-damaged portions of the outer wall ofthe tunnel. The method of repairing can include using the imagingdevice, or a different imaging device, to determine the locations ofanchors within and near the damaged portion of the tunnel (step S2).Identifying the anchor locations can allow for consistent distributionof anchors on/in the wall replacement portion. In some embodiments, themethod of repair includes marking the tunnel (e.g., the outer surface ofthe tunnel) to define the portion of the wall to be replaced (step S3).Marking the tunnel can include painting, etching, and/or other methodsof marking. Preferably, the marked area has four sides, with one or moresides parallel to the length of the tunnel and one or more sidesperpendicular to the length of the tunnel. In some embodiments, themethod of repair includes cutting a replacement outer wall from a metalstock piece (step S4). The replacement piece can be rolled or otherwiseshaped to match the contours of the surrounding tunnel.

In some embodiments, the method of repairing the tunnel includes cuttingout (e.g., laser cutting, drilling, sawing, chain-sawing, or othercutting) the portion of wall to be replaced (step S5). The cutting canbe performed along the markings previously made on the outer wall of thetunnel. Preferably, the cutting is performed on an area larger than thedamaged area to reduce the likelihood that the repair process fails tocapture some portion of damaged tunnel. In some embodiments, the methodof repairing the tunnel includes cutting an access port or window inanother portion of the common tunnel (step S6). For example, it may beadvantageous to cut an access port in a portion of the tunnel oppositethe repair site. In some embodiments, the access port is cut in a lowerportion of the tunnel near the repair site. Cutting the access port in alower portion of the tunnel can allow for easier cleaning of the tunnel(e.g., removal of debris from cutting the damaged portion of tunnel).Removing debris/excess or damaged insulation can increase draft withinthe tunnel. In some embodiments, an uptake duct, stack, or other pathwayis used in addition to instead of cutting an access port. The accessport can allow the repair personnel to install the replacement tunnelportion (step S7). For example, insulation can be gunned or otherwisedeposited onto the inner surface of the replacement wall portion throughthe access port. In some embodiments, portions of the internalinsulation of the tunnel are removed or repaired via the access portduring or before installation of the replacement wall portion. In someembodiments, the replacement wall portion is welded (e.g., tackwelded)from one or both of the inside of the tunnel via the access port andfrom outside of the tunnel.

In some embodiments, braces or other supports are installed (e.g.,temporarily or permanently) on the tunnel upstream and/or downstream ofthe repair site. The supports can reduce the likelihood of damage to thetunnel during and/or after cutting of the damaged portion and/or cuttingof the access port(s).

In some embodiments, insulation and/or mastic material is deposited onthe inner surface of the replacement wall portion before or afterwelding the replacement wall portion to the surrounding tunnel. Forexample, refractory can be attached to the inner surface of thereplacement wall portion. The refractory can be scored to increaseflexibility and conformance with the curvature of the inner surface ofthe replacement wall portion. In some embodiments, anchors are installedon the replacement wall portion before or after attachment of therefractory material and/or other insulating material. The anchors can bedrilled through the outer wall or the replacement wall portion orconnected to an inner surface of the outer wall. The anchors can bearranged in a pattern similar to or the same as the pattern observed instep S2. For repair of cold portions of tunnel (e.g., tunnel portionscolder than 500° F.), insulation may be used on an outer surface of thetunnel instead of or in addition to insulation on an inner surface ofthe outer wall of the tunnel.

In some embodiments, exhaust stacks (e.g., bypass exhaust stacks) on oneor both side of the repair site are opened to permit repair of thetunnel at the repair site. Opening the exhaust stacks can lower thetemperature of the repair site and/or remove harmful gases from therepair site. Upon completion of the repair, the exhaust stacks can bereturned to a closed configuration.

As utilized herein, the terms “approximately,” “about,” “substantially,”and similar terms are intended to have a broad meaning in harmony withthe common and accepted usage by those of ordinary skill in the art towhich the subject matter of this disclosure pertains. It should beunderstood by those of skill in the art who review this disclosure thatthese terms are intended to allow a description of certain featuresdescribed and claimed without restricting the scope of these features tothe precise numerical ranges provided. Accordingly, these terms shouldbe interpreted as indicating that insubstantial or inconsequentialmodifications or alterations of the subject matter described and areconsidered to be within the scope of the disclosure.

It should be noted that the term “exemplary” as used herein to describevarious embodiments is intended to indicate that such embodiments arepossible examples, representations, and/or illustrations of possibleembodiments (and such term is not intended to connote that suchembodiments are necessarily extraordinary or superlative examples).

It should be noted that the orientation of various elements may differaccording to other exemplary embodiments, and that such variations areintended to be encompassed by the present disclosure.

It is also important to note that the constructions and arrangements ofthe apparatus, systems, and methods as described and shown in thevarious exemplary embodiments are illustrative only. Although only a fewembodiments have been described in detail in this disclosure, thoseskilled in the art who review this disclosure will readily appreciatethat many modifications are possible (e.g., variations in sizes,dimensions, structures, shapes and proportions of the various elements,values of parameters, mounting arrangements, use of materials,orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter recited in the claims.For example, elements shown as integrally formed may be constructed ofmultiple parts or elements, the position of elements may be reversed orotherwise varied, and the nature or number of discrete elements orpositions may be altered or varied. The order or sequence of any processor method steps may be varied or re-sequenced according to alternativeembodiments. Other substitutions, modifications, changes and omissionsmay also be made in the design, operating conditions and arrangement ofthe various exemplary embodiments without departing from the scope ofthe present disclosure. For example, while many aspects of the presenttechnology are described in the context of HHR/heat recovery systems,many or most of the devices, systems, and methods described herein canbe implemented in non-recovery applications (e.g., horizontalnon-recovery coke ovens, beehive/non-recovery coke plants, and/or othernon-recovery systems).

As used herein, the terms “coke plants”, “coking plants”, “cokesystems,” “coking systems,” “systems for coking coal,” and theirvariants collectively refer to any type of coke plant, includingbyproduct coke plants, heat recovery coke plants, horizontal heatrecovery coke plants, non-recovery coke plants, and horizontalnon-recovery coke plants. Moreover, certain aspects of the presentdisclosure are described in the context of a specific oven type.However, as one skilled in the art will appreciate, such aspects may bereadily adapted for use with any type of coke plant. Accordingly,aspects of the present disclosure is not limited to a specific type ofcoke plant, unless explicitly noted otherwise.

The present disclosure contemplates methods, systems and programproducts on any machine-readable media for accomplishing variousoperations. The embodiments of the present disclosure may be implementedusing existing computer processors, or by a special purpose computerprocessor for an appropriate system, incorporated for this or anotherpurpose, or by a hardwired system. Embodiments within the scope of thepresent disclosure include program products comprising machine-readablemedia for carrying or having machine-executable instructions or datastructures stored thereon. Such machine-readable media can be anyavailable media that can be accessed by a general purpose or specialpurpose computer or other machine with a processor. By way of example,such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, CD-ROMor other optical disk storage, magnetic disk storage or other magneticstorage devices, or any other medium which can be used to carry or storedesired program code in the form of machine-executable instructions ordata structures and which can be accessed by a general purpose orspecial purpose computer or other machine with a processor. Wheninformation is transferred or provided over a network or anothercommunications connection (either hardwired, wireless, or a combinationof hardwired or wireless) to a machine, the machine properly views theconnection as a machine-readable medium. Thus, any such connection isproperly termed a machine-readable medium. Combinations of the above arealso included within the scope of machine-readable media.Machine-executable instructions include, for example, instructions anddata which cause a general purpose computer, special purpose computer,or special purpose processing machines to perform a certain function orgroup of functions.

We claim:
 1. A method of repairing a tunnel in a coke plant, the methodcomprising: removing a first portion of a wall of the tunnel; forming areplacement outer wall portion, the replacement wall portion having asize substantially similar to or larger than the first portion of thewall removed from the wall; connecting a plurality of anchors to thereplacement outer wall portion, each anchor comprising a wall-attachmentportion and an anchoring portion; connecting the replacement outer wallportion to the tunnel in place of the removed first portion of the wall;depositing a refractory material on an inner portion of the replacementouter wall portion; and sealing a perimeter of the replacement outerwall portion with respect to the tunnel; wherein: the plurality ofanchors are distributed in a pattern such that a maximum spacing betweenthe anchors is less than twelve inches.
 2. The method of claim 1,wherein an area with highest anchor density is located at an uppermostportion of the replacement outer wall portion as determined when thereplacement outer wall portion is connected to the tunnel in place ofthe removed first portion of the wall.
 3. The method of claim 1, whereina majority of the anchors are distributed in a staggered row pattern onthe replacement outer wall portion.
 4. The method of claim 1, furthercomprising connecting a refractory backer board to the anchors beforedepositing the refractory material on the inner portion of thereplacement outer wall portion, wherein the refractory backer board ispositioned between the replacement outer wall portion and the refractorymaterial after the refractory material is deposited.
 5. The method ofclaim 4, wherein the refractory backer board is at least two inchesthick as measured normal to a surface of the replacement outer wall. 6.The method of claim 1, wherein depositing the refractory material on theinner portion of the replacement outer wall portion includes gunning therefractory material onto the inner portion of the replacement outer wallportion.
 7. The method of claim 1, wherein depositing the refractorymaterial on the inner portion of the replacement outer wall portionincludes shotcreting the refractory material onto the inner portion ofthe replacement outer wall portion.
 8. The method of claim 1, furthercomprising identifying the first portion of the wall as a portion havingdamage.
 9. The method of claim 8, further comprising using infraredimaging to determine a boundary of the damage.
 10. The method of claim9, further comprising defining a perimeter of the first portion of thewall to be replaced outside of the boundary of the damage.
 11. Themethod of claim 1, wherein the refractory material is configured towithstand heats of at least 2200° F.
 12. The method of claim 1, whereinthe refractory material is configured to withstand heats of at least3200° F.
 13. The method of claim 1, wherein one or more of the anchorscomprises at least two anchoring prongs.
 14. The method of claim 13,wherein the anchoring prongs are bent in at least two locations along alength of the anchoring prongs.
 15. The method of claim 1, whereindepositing the refractory material on the inner portion of thereplacement outer wall portion comprises shooting the refractorymaterial through an opening in the tunnel.
 16. The method of claim 1,further comprising coating an inner surface of the replacement outerwall portion with a mastic or other corrosion-resistant material. 17.The method of claim 1, further comprising tack welding the replacementouter wall portion to the tunnel prior to depositing the refractorymaterial on the inner portion of the replacement outer wall portion. 18.The method of claim 1, wherein a minimum spacing between the anchors isless than or equal to six inches.
 19. The method of claim 9, whereinremoving the first portion of the wall of the tunnel comprises cutting aportion of the wall of the tunnel outside of the boundary of the damage.20. The method of claim 1, wherein anchors positioned around theperimeter of the replacement wall portion are longer than other anchorsand/or are distributed at a higher density than anchors on otherportions of the replacement wall portion.